fix: correctly filter IPs from CIDR during aggregation

Author: jjhwan-h

cmd/mapcidr/main.go

@@ -384,7 +384,6 @@ func process(wg *sync.WaitGroup, chancidr, outputchan chan string) {
 	)
 
 	ranger, _ = ipranger.New()
-
 	for cidr := range chancidr {
 		// if it's an ip turn it into a cidr
 		if ip := net.ParseIP(cidr); ip != nil {
@@ -453,8 +452,22 @@ func process(wg *sync.WaitGroup, chancidr, outputchan chan string) {
 				continue
 			}
 
-			// In case of coalesce/shuffle we need to know all the cidrs and aggregate them by calling the proper function
-			if options.Aggregate || options.Shuffle || hasSort || options.AggregateApprox || options.Count {
+			if len(options.FilterIP) != 0 {
+				for _, ip := range getIPList([]*net.IPNet{pCidr}) {
+					if options.FilterIP != nil && sliceutil.Contains(options.FilterIP, ip.String()) {
+						continue
+					}
+					singleCIDR := &net.IPNet{
+						IP:   ip,
+						Mask: net.CIDRMask(len(ip)*8, len(ip)*8),
+					}
+					allCidrs = append(allCidrs, singleCIDR)
+				}
+				if options.Aggregate || options.Shuffle || hasSort || options.AggregateApprox || options.Count {
+					_ = ranger.Add(cidr)
+				}
+			} else if options.Aggregate || options.Shuffle || hasSort || options.AggregateApprox || options.Count {
+				// In case of coalesce/shuffle we need to know all the cidrs and aggregate them by calling the proper function
 				_ = ranger.Add(cidr)
 				allCidrs = append(allCidrs, pCidr)
 			} else {

cmd/mapcidr/main_test.go

@@ -220,6 +220,16 @@ func TestProcess(t *testing.T) {
 				SortDescending: true,
 			},
 			expectedOutput: []string{"192.168.1.3", "192.168.1.2", "192.168.1.1", "192.168.1.0"},
+		}, {
+			name:       "FilterIPWithAggregation",
+			chancidr:   make(chan string),
+			outputchan: make(chan string),
+			options: Options{
+				FileCidr:  []string{"10.0.0.0/30"},
+				FilterIP:  []string{"10.0.0.1"},
+				Aggregate: true,
+			},
+			expectedOutput: []string{"10.0.0.0/32", "10.0.0.2/31"},
 		},
 	}
 	var wg sync.WaitGroup

ip.go

@@ -279,8 +279,8 @@ func ipNetToRange(ipNet net.IPNet) netWithRange {
 	firstIP = firstIP.Mask(ipNet.Mask)
 	lastIP = lastIP.Mask(ipNet.Mask)
 
-	if firstIP.To4() != nil {
-		firstIP = append(v4Mappedv6Prefix, firstIP...)
+	if ip4 := firstIP.To4(); ip4 != nil && !(len(firstIP) == net.IPv6len && bytes.Equal(firstIP[:12], v4Mappedv6Prefix)) {
+		firstIP = append(v4Mappedv6Prefix, ip4...)
 		lastIP = append(v4Mappedv6Prefix, lastIP...)
 	}